Tokkai Hei 9-303173 published by the Japan Patent Office in 1998 which concerns fuel injection control of an internal combustion engine, discloses a method of calculating fuel injection amount using a wall flow model. Wall flow means the fuel flow which is formed when some of the fuel injected from the fuel injector adheres to a wall surface of a combustion chamber or an intake port, or to an intake valve. Part of the wall flow vaporizes and burns, and part vaporizes after combustion is complete and is discharged from an exhaust valve without being burnt. The remaining part of the wall flow remains in the combustion chamber until the following combustion cycle.
The ratio of the injected fuel which forms a wall flow is known as an adhesion ratio. Of the fuel forming the wall flow, the ratio of fuel which remains in the combustion chamber in the wall flow state without vaporizing, is known as a residual ratio.
The prior art proposes to construct a behavior model of injected fuel according to the adhesion ratio and residual ratio as parameters. By varying the parameters based on the intake air pressure, the behavior of the fuel supplied to the internal combustion engine is precisely analyzed, thereby enhancing the precision of fuel supply control. Such a behavior model decreases the work amount of the experiments required for adaptation of fuel supply control to respective internal combustion engines and shortens the time required for the development of a new engine.